Long term plasticity is essential for the proper function of the striatum. It occurs on a timescale of tens of minutes and putatively underlies habit formation and learning. The delicate balance between long term potentiation and long term depression is important for correct motor and cognitive function and is disrupted in striatal based diseases such as Parkinson's Disease (Calabresi et al., 2007). Many molecules are necessary for long term plasticity, but exactly where they need to be active is not well established. Cyclic AMP dependent protein kinase (PKA) is one such molecule. Long term potentiation (LTP) of striatal synapses requires active PKA, but PKA is not randomly located within a neuron. PKA is localized to specific areas of the neuron by A-kinase anchoring proteins (AKAPs). This study investigates where PKA must be active for cortico- striatal LTP to occur. Using electrophysiology, pharmacology, and transgenic mice, I will test whether PKA needs to be anchored pre- or post-synaptically, and whether it needs to be concentrated close to its phosphorylation targets or close to the source of cAMP. I will also investigate the role of one particular AKAP, AKAP150, which has been implicated in striatal learning tasks, but whose role in cortico-striatal plasticity is unknown (Weisenhaus et al., 2010). An in-depth analysis of PKA anchoring in the striatum is an essential step in understanding the intracellular signaling cascades that underlie striatal plasticity. A complete understanding of these pathways will guide research to novel drug targets that address both the motor and the cognitive deficits of Parkinson's Disease. PUBLIC HEALTH RELEVANCE: The correct balance between the strengthening and weakening of neuronal pathways is essential for proper brain function. A disruption of this balance in the dorsal striatum may be the cause of motor and cognitive deficits associated with Parkinson's Disease. This project will examine specific mechanisms underlying the strengthening of dorsal striatum pathways and will yield information helpful for establishing new drug targets and evaluating current treatments for Parkinson's Disease.